MonarchX, do youself a favour and dont listen too much to the flying "hey, my X is greater than anything in universe". Your observation regarding Tenebrium is correct, your damage values decent enough for the level.
I am used to fight with gear up to 10 levels down my character level, because the combination on a specific gear is more important than one better value on a newer one.
Regarding builds I have yet to see really decent advice. Which would e.g. be to skip the "Uber" warrior 2 hand build with 25 strength and instead give him a few points for intel and some magic abilities for enemy disabling.
I am sure my last party (now level 14) does less damage than average and less than my last parties. But it has the combined ability to take 5 or 6 single enemy figures out of the fight in the first turn and keep them disabled during the fight. Means I need a bit more time to kill, but my party does it risk free. I only needed 2 healings at the end of my last 4 fights (Goblins and Luculla mines) because no enemy ever got to strike.
And if you happen to have a character who has already a 5 in single handed, simply forget Tenebrium. It is irrelevant.
Regards,
Thorsten